The present invention relates to venetian blind assemblies and more specifically to novel method and apparatus for forming the ladders supporting the slats in these assemblies.
Conventional venetian blind assemblies usually comprise a head rail mounted in the top section of a window opening or the like, a plurality of horizontally oriented vertically spaced slats supported in ladders adjacent their outer terminal ends, and a bottom rail to which the lower end of the ladders are connected. The head rail houses control mechanisms for raising and lowering the slats as well as means including a tilt control bar for changing the angular attitude of the slats. The ladders are secured to the tilt control rod at their upper ends in some cases by looping the ladder around the tilt control rod. Venetian blinds of this general type are shown in Walker U.S. Pat. Nos. 2,663,368 and 2,892,493 and Rau U.S. Pat. No. 3,180,400. As illustrated in these prior patents, the ladders usually comprise a pair of vertical or upright cords which at their upper ends may be looped or otherwise secured to the tilt control rod and a series of transverse vertically spaced cross pieces or rungs on which the slats rest. Some of these ladder assemblies are of the so called "string" type wherein the side pieces are braided cords and each cross piece is a plurality of filaments which may be braided or twisted into one or more strands. The present invention is adapted particularly for making ladders of this type.
The stock material for these string type ladders is usually available in a long continuous length which the manufacturer of the blind assembly cuts to a given length depending on the type and size blind assembly. After cutting lengths from the ladder stock the upper ends of the vertical strings are then secured and at least two or three of the cross pieces adjacent the top are trimmed in the manner shown in FIG. 1 of the drawings to allow for looping around the tilt control rod. The bottom terminal ends of the vertical cords are attached to a bottom rail by means of a fastening button or the like. Preparation of the ladders heretofore has been done manually which of course is somewhat time consuming and expensive. The string type ladder is particularly difficult to handle because it is so delicate and the cords and cross pieces tend to tangle and twist in handling from the stock material.